Haemoglobin receptor protein is intragenically encoded by the cysteine proteinase-encoding genes and the haemagglutinin-encoding gene of Porphyromonas gingivalis.
The obligately anaerobic bacterium Porphyromonas gingivalis produces characteristic black-pigmented colonies on blood agar. It is thought that the black pigmentation is caused by haem accumulation and is related to virulence of the microorganism. P. gingivalis cells expressed a prominent 19 kDa protein when grown on blood agar plates. Analysis of its N-terminal amino acid sequence indicated that the 19 kDa protein was encoded by an internal region (HGP15 domain) of an arginine-specific cysteine proteinase (Arg-gingipain, RGP)-encoding gene (rgp1) and was also present in genes for lysine-specific cysteine proteinases (prtP and kgp) and a haemagglutinin (hagA) of P. gingivalis. The HGP15 domain protein was purified from an HGP15-overproducing Escherichia coli and was found to have the ability to bind to haemoglobin in a pH-dependent manner. The anti-HGP15 antiserum reacted with the 19 kDa haemoglobin-binding protein in the envelope of P. gingivalis. P. gingivalis wild-type strain showed pH-dependent haemoglobin adsorption, whereas its non-pigmented mutants that produced no HGP15-related proteins showed deficiency in haemoglobin adsorption. These results strongly indicate a close relationship among HGP15 production, haemoglobin adsorption and haem accumulation of P. gingivalis.
Nakayama
K
K
Department of Microbiology, Kyushu University, Fukuoka, Japan. kojidef@mbox.nc.kyushu-u.ac.jp
Ratnayake
D B
DB
Tsukuba
T
T
Kadowaki
T
T
Yamamoto
K
K
Fujimura
S
S
D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D002847:Chromatography, Agarose; D003546:Cysteine Endopeptidases / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D006388:Hemagglutinins / Q000235:genetics*; D006454:Hemoglobins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000737:chemistry; D016133:Polymerase Chain Reaction; D016966:Porphyromonas gingivalis / Q000235:genetics* / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000235:genetics*; D017422:Sequence Analysis, DNA
D004269:DNA, Bacterial; D006388:Hemagglutinins; D006454:Hemoglobins; D011956:Receptors, Cell Surface; D003546:Cysteine Endopeptidases